In my general experience online on sites like these and previously on v6camaro.com I've come across a huge trend that really is nothing new but I believe is GROSSLY misunderstood and not particularly well used. The optional temperature thermostat.

"Back in the day" The solution to low grade fuels in higher performance engines (That ran pig rich and comparatively VERY inefficiently) was obviously not to reduce power by pulling timing (You could not do that "on the fly', no knock sensors) You could not obviously reduce compression easily, and you very well had to spend a good half hour if you wanted to re-jet your carburetor to get more fuel in the cylinders to cool them down and prevent knock. Certainly an easy task now a days with just a few clicks of the mouse.

So? Well by golly put a colder T-stat in it! Lower running temps must = better power because we can advance timing more and get more power out of the fuel we are dumping into the cylinders.

Then we had knock sensors, now spark timing was controlled to a certain extent and we no longer had to worry about being able to throw timing at it. Therfore no need to worry about pings, knocks, or detonation.

All fine and good until the 70's hit and we began to be concerned with emissions. A little Agency called the EPA decided they wanted to restrict what came out of our tailpipes.

One of the biggest advances in Air/Fuel delivery was when it was noted that cold start emissions are the highest. Still holding true today it takes over 25-40% more fuel to start a cold engine then to start a warm engine. So whats the catch? Automakers had to find a way to get the engine up to temperature as quickly as possible. This led to things such as thermostatic switches that opened doors in Air filter housings so air was drawn from around the exhaust manifolds (Got hot first) and pulled into the air filter considerably warmer then ambient. This helped atomize the fuel better and we STILL see if today in throttle bodies with coolant jackets in them and intake manifolds with coolant passages in them.

The bottom lines are this...Engines make power by converting chemically stored energy in gasoline into heat and heat into motion via the pistons and crankshaft. So why on gods earth would you put a thermostat thats 20 degrees cooler than the manufacturer intended into any engine big or small that you look to make serious horsepower with? The point of ceramic coatings on piston tops and cylinder heads is to keep heat in so it can more effectively be converted into power for a longer amount of time. So why would you want that engine at anything less than full operating temperature?

This also calls to mind something that in carburation is important. What about the vaporization of the fuel? Fuel vapor burns, Liquid gasoline DOES NOT. So the faster we can get the fuel Vaporized (Hotter Temperature we can get it in its short trip to the valve) The better. Again, why would you ever want any less heat in the engine than whats already there? Fuel injection helps alot with this, but fuel Vaporization is still a BIG issue especially with higher revving engines today, theres simply less time to get the same work done.

In the OEM world, we have seen steadily an increase in thermostat temps, I dont see why we won't see engines happily running at 205-220 no problem for their lifetime and get better fuel economy and better power out of it.

The big question is...do you NEED a cooler thermostat? I dont think so, I dont run one, I wont run one, ever, Instead with the capabilities we have in tuning I think we should at least aim to keep coolant temps in the stock range, as that is what the engines are happiest running at as per OE. Keep in mind EVERY clearance in an engine takes into account thermal expansion...IF it were my engine and I was not willing to rebuild it at the very least every season, I would go with the specified clearances and of course, get it up to operating temp as quickly as possible to minimize the amount of time that elapses when parts are damaged and suffer the most wear due to being cold. There is alot of misinformation about alot of things and I think running a cooler thermostat is construed as a good thing when in reality its about as useless as a "tornado air management system" Its right up there on my list of things that demonstrate an ignorance to what it takes to make workable and useable power on todays engines along with "well Im going to put a header on my car cause it flows better" coming from a person who's done no head work...

So if it were up to me, I would recommend a stock thermostat, a premium one, but otherwise OE temperature and configuration. OEM cooling systems are MORE than adequate to support horsepower levels in excess of 30-50%. Beyond that, the first thing is a radiator.

So folks, moral of the story, dont touch your thermostat!



Buildin' n' Boostin for 08' - Alex Richards

good read. I work at a parts store and i see people do this on a daily basis, no matter how hard i try to convince them to use a factory temp stat they just tell me i dont know any better and to give them the one they want.

Devils advocate:

Guy with 2.2 telling everyone with big manly engine how to make power.

I'm kidding!

LOL



You're right for the most part though, though the general drop is people going from a 195 to a 180 so that's 15 degrees. The thermostat regulated 15 degrees probably isn't worth much once these modern fuel injected engines are up to operating temp and ready to be beaten on. At least that's my opinion.

I still however would put header(s) on any car with a stock head. The way you stated that in your post makes you seem like an elitist. A well designed header(s) will still make workable and usable power as you put it.